Fossil Fuel

What Is Coal?

Coal is a black or brownish-black burnable fossil fuel, containing the remnants of plant and animal matter that can be burnt to provide energy. Coal contains elements such as hydrogen, oxygen, and nitrogen as well as numerous minerals but it consist largely of carbon.

How Was Coal Formed?

It is understood that Coal was formed during the Carboniferous period (280 to 345 million years ago) when large amounts of organic materials such as plant life grew in swamp like conditions. When the organic matter eventually died it would drift to the bottom of the swamp, decompose slowly over time, turn into peat and as the peat was compressed under the earths surface over millions of years it would turn into coal through the forces of pressure and heat over time. The higher the level of compression and heat, the harder the coal would be produced.

Where Can Coal Be Found?

Coal can be found in every continent on the planet, including unlikely regions such as Antarctica. This is due to the way in which the fossil fuel is formed over millions of years from dead plants and organic materials.

How Do We Get Coal?

We get coal from the ground by mining for it. Coal miners will use large mining machines to extract the coal by one of two ways –

• Surface mining
• Underground mining

Surface mining consists of the mining for coal no deeper than 200 feet underground. Surface mining is much cheaper than underground mining and in the US it is estimated that two thirds of all coal production of obtained from surface mining because in the US, much of the coal reserves are located near to the grounds surface. To surface mine coal, it is necessary to use machines to remove the topsoil and large layers of rock to expose the coal beds. Once the coal has been mined, the miners will return the rock and topsoil to the cavity in the earth to allow for the area to be used for replanting, agriculture, buildings wildlife areas or one of a number of uses.

Underground mining is the more expensive and dangerous option, which will allow miners to extract coal from 1,000 feet or more underground. Essentially, two large openings called “shafts” will need to be drilled into the ground. The first is to allow the transport of miners and machinery underground to the coal itself and the second shaft is drilled to transport the mined coal to the surface. The coal will then need to be broken down into a manageable size by conventional mining techniques, the use of large machinery incorporating rotating cutters or the use of explosives.

How Do We Transport Coal?

Once the coal has been mined from the ground and broken down into manageable pieces it will be transported by a variety of transport methods. The most popular transport method for coal is by railway, although it is also carried by truck, conveyors, and by boat.

Name The Different Types of Coal?

Coal can be broken down into four main types which is based upon the amount of pressure and heat that was used to create the coal over millions of years in the earth and also by the amount of carbon that is in the coal.

The four main types of coal are –

• Anthracite
• Bituminous
• Subbituminous
• Lignite

Anthracite has the highest concentration of carbon (between 85% – 97% carbon) and has a slightly lower heating rate than bituminous coal.

Bituminous coal contains 45% – 86% carbon and has a high heating value. For this reason it is a very important fossil fuel for the steel and iron industries and it is widely used to generate electricity. It is a highly abundant form of coal and it was formed between 100 – 300 million years ago.

Subbituminous coal will typically contain 35% – 45% carbon and has a slightly higher heat rating than that of lignite coal. Again subbituminous is an abundant form of coal and it is thought to have been formed 100 million years ago.

Lignite coal will typically contain 25% – 35% carbon and has the lowest coal energy rating. The reason for this is that deposits of lignite are relatively young so they have not been subjected to extreme heat and pressure over the long periods of time that other forms of coal have and as such this type of coal is quite brittle and moist.

Generally speaking the energy rank of a type of coal will be dependent on the heat and pressure that it has withstood over the years so the higher the pressure and heat it has withstood and the longer it has withstood it, the greater the heating rank it will be.

What Do We Use Coal For?

Coal is primarily used for the production of electricity both domestically and for industry. The main areas that it is used are:

• Electricity production
• Exports
• Making steel
• General industry

Electricity production by burning coal amounts to almost half of the electricity produced in the US alone. Power plants burn coal to make steam and the steam will power turbines in the power plant, which will generate the electricity.

Exports of coal in the US amount to approximately 9% and these exports will go to many of the world’s major nations. In 2005, 49.9 million tonnes was exported to other countries from the United States.

The use of coal in making steel is very important. Coal is baked in hot furnaces to make coke, which can be used to smelt iron ore into iron, which can then be used to make steel. It is the high temperatures that are obtained by burning coke that helps give steel the strength and flexibility needed.

In industry coal is burnt to produce numerous products and by-products of coal. Burning coal itself can create the by-products methanol and ethylene, which can be used in making plastics fertilisers and medicines. Also the paper and concrete industries burn significant amounts of coal to operate.

How Much Coal Is Left?

The United States has approximately 268 billion tons of recoverable coal remaining, which should last for another 250 years if the rate of use stays at the same level as today.

Worldwide, there is approximately 998 billion tons of recoverable coal sitting underground according to an estimate in 2006 from the International Energy Agency. The countries with the highest deposits (in order) are –

• United States – 268 billion tons
• Russia – 173 billion tons
• China – 126 billion tons
• India – 102 billion tons

These four countries hold around two thirds of the worlds coal supplies.

Why Do We Use Coal to Generate Electricity?

Very simply, coal is widely used to generate electricity because it is an abundant fossil fuel, which is also comparatively cheap to obtain and to turn into energy.

How Fast Is Demand Growing For Coal?

Coal demand is growing steadily with 26% of all energy consumed in 2004 worldwide being derived from burning coal according to the U.S. Energy Information Agency. It is thought that this figure will grow to be 38% by 2030.

Increased carbon taxes and a general awareness of possible environmental concerns about the production of energy via coal are resulting in lower growth rates of the use of coal in the developed nations. Developing nations, with a 72% rise predicted over the next 25 years by India and China, will fuel growth in the use of coal.

How Much Does Coal Cost?

Thirty-five years ago it was cheaper to produce electricity by using natural gas, but in the late 1970’s coal became the cheapest fossil fuel for producing energy and it remains the cheapest to this day.

In 2005, generating a million BTUs from coal would cost $1.54, compared with $8.20 for natural gas.

Does Coal Cause Pollution?

In a word, yes. Coal accounted for 39% of all carbon dioxide emissions in 2004 (this behind oil) but it is expected to pass oil for the highest levels of carbon dioxide emissions in 2010, according to the EIA. Tellingly, if residents in the US were to replace every incandescent light bulb in the country with compact fluorescents, the benefits would be eradicated by the carbon dioxide from only two coal-fired plants over the period of a year.

Other pollutants that can be attributed to the burning of coal can include nitrogen compounds, sulphur, aluminium, and silicon. Environmental and health related problems include acid rain, polluted water systems, stripped forests, and mining hazards.

How Can Coal Be Cleaned To Lower Pollution?

There are a number of experimental techniques that are currently being developed which will hopefully lead to lower emissions from burning coal. A brief list of these is –

• Convert coal into natural gas, which is a cleaner fossil fuel. Carbon dioxide produced during the conversion will get sequestered at plants. Although studies show that converting fossil fuels can be somewhat energy inefficient as there can be “leakage” of energy.
• Develop more efficient boilers that cut down on the amount of pollutants being released from the burning of coal.
• Convert coal into a liquid fuel, which could be used to power cars.

What Is Carbon Capture?

Carbon capture is the process whereby it is attempted to remove the harmful elements in the emissions created when burning coal. Due to the massive reliance globally on coal as an energy resource, it is unlikely to be removed overnight so it is important to develop ideas to burn coal more cleanly and this is the essence of carbon capture techniques.